1. Field of the Invention
This invention relates to a method and related apparatus for reversibly occluding a biological tube within a body to control the flow of matter through the tube. The method further contemplates removal of the obstruction using lithotripsy techniques to fragment the occluding device, and thereby clear the tube once again.
2. Background Information
In many applications in the medical and scientific research fields, it is necessary or desirable to arrest normal or abnormal function of a biological tube by blocking or occluding flow or passage through the tube of fluids or solids. Many procedures which have been known for occluding a body tube are discussed hereinafter. Such procedures often require surgical introduction of the occluding device into the body tube. In most cases the device cannot be removed without further surgery.
One particular field where occlusion of a body passage is important today is that of fertility limitation or sterilization. The problem encountered with the most prevalent method of both female and male sterilization is that of non-reversibility. In male sterilization, generally a vasectomy is performed by surgically severing the vas deferens. Alternatively, a method is used for tying off the vas deferens.
Similarly in female sterilization, a surgical procedure is necessary to prevent transport of ova through the oviduct. Again, either surgical severance of the oviduct is required or a tying procedure is used.
The problem, however, which is presented with both male and female sterilization is that of reversibility. The procedures currently being used are essentially non-reversible. Therefore the decision to undergo such a procedure is one from which a person cannot retreat. However, if reversibility of such procedure were to become dependable, simple and inexpensive, then more individuals may opt for these procedures as methods of fertility control.
There are also many other situations which require blocking of body passages. For example, there may be cases where surgical procedures require occlusion of a blood vessel temporarily or that fistulae or intracranial or intraspinal vascular malformations be blocked off from normally functioning vessels and ducts.
As mentioned hereinbefore, methods have been known for occlusion of body tubes. For example, various types of plugs have been known to occlude the vas deferens for blocking the flow of sperm. U.S. Pat. No. 3,422,813 discloses such a plug, however, surgical removal of the occlusion would be required.
Other methods include valves which may be introduced into such passages. See U.S. Pat. No. 3,731,670 which discloses a magnetic duct valve, and U.S. Pat. No. 4,200,088 which discloses a plug member.
Various devices have also been known which are introduced into a duct and which, after coming into contact with the water in the body, swell up and tightly fit within the body duct in which they are introduced. See U.S Pat. Nos. 4,365,621 and 4,509,504.
Other devices have been known which again, require surgical removal when they are no longer necessary or desired. See U.S. Pat. No. 4,512,342.
In spite of the foregoing attempts there remains a need for an improved method and related apparatus for occluding a biological passage or tube and, in particular, for sterilization by such occlusion, which is reversible and which does not require invasive technique for the reversal of the occlusion. There is also a need for such a method whereby the occluding device ma be introduced into the tube without the necessity of surgery.